thanks for all the pointers and ideas- it seems that the catalog page was missing a bit of info that the data sheet filled in. who would have thought it

to move this thing in direction "A", apply a voltage to pin D, this voltage is ranging from 0-10v. to move this thing in direction "B", apply 0-10v to pin E.

pin D and pin E are to remain connected to their respective branches of the circuit. i would imagine i could break something it 10v was on pin D and pin E at the same time?

the data sheet says that if only one signal pin is available, then the other needs to be grounded. since i will be using both signal pins - there is no need to ground the pin, when traveling in the opposite direction, correct?

i'll keep reading a bit and post a circuit sketch in a bit -- again thanks for the help

I agree with dc42 that his ckt should work, and all the way from 0V to 10V output, as the LM358opAmp has input common-mode range down to ground.

The one thing that may be an issue is that 1st-order filtering of the PWM signal will leave a little ripple on the DC-level, so the valve may jitter some. You can deal with that by using a PWMfrequency much much greater than the R*C time constant of his filter, but this will also reducethe frequency response of the valve, if that's an issue.

...filtering of the PWMso if i look at it on a scope i'll see some stepped lines, and not super smooth, the faster the pwm frequency, the less noticeably this becomes?

...PWM frequency much much greater than the R*C time constant of his filter the math of circuits has got me confused. i used to have respectable math skills, but haven't used them in many years. could you clarify a bit.

For a 1st-order RC low-pass filter, the 3dB or 'cutoff' frequency is given by F3db = 1/(2*pi*R*C). You want the PWM frequency to be maybe 5X this value to get reasonably small ripple. Probably better to directly accessthe Arduino PWM subsystem than to use the analogWrite() function, which I believe has a fairly low frequency.

BTW, I find I'm using google images for almost everything now, in preference to a regular google search. Easierto zero in on the perfect website, :-).

I'm confused at where the RC filter would be connected in the circuit. If I was switching a transistor with one of the pwm pins, the transistor is allowing the path to ground. Is the RC filter on the collector side or the emitter side? (thinking this is an NPN)

There is a path to ground via the capacitor, is the high freq. stuff is going this route? and that's the whole point...

No that is totally wrong.Collector to pull up resistor to +12V.Collector to filter resistor. Other end of resistor to capacitor to ground and also to one of the inputs of your controller.You need two of these circuits one for each input. You also need a common ground.